He was identified as the eldest son in a will written by his father in 1707. He was left a gun, pistols, and holsters to satisfy the "eldest son" requirement of English inheritance law. In 1714, he also was named among the heirs in the will filed by his grandfather.

After that, the name of this Willem Vandenbergh appears to be absent from Albany rolls. He was not named in the will filed by his mother in 1745 - a document in which his younger brother, Adam, was called her eldest son.